Traditional and common skimmers generally have vertical sides with a lower open bottom. The vertical sides make use of a hydraulic pressure differential between the front side and back side of the skimmer to direct the water flow down and pass it through the open bottom. Once the flow passes through the open bottom flow will be conveyed downstream. The intention is that debris or liquids that float due to buoyancy will not be able to move downward into the water column to pass through the open bottom of the skimmer.
A problem with the traditional and common skimmers is the balance between headloss that they create and the need to pass water flow to prevent flooding. When the opening under a skimmer is relatively large it will have less headloss, a greater water conveyance, but less treatment potential. When the opening is relatively small under a skimmer it will have greater headloss, less water conveyance, but greater treatment.
As such, the traditional and common skimmers do not allow for maximum detention time to allow for capturing contaminates such as foliage, litter, and sediments, and lighter than water liquids such as petroleum products. In short, to treat the storm water flow to prevent pollutants from being conveyed downstream to a receiving body of water. This process of treating the water flow can create headloss which could impede the flow and reduce the rate of flow.
Additionally, if the treatment results in a significant reduction in the rate of flow, flooding can occur upstream from the stormwater treatment structure.
As such, minimizing the headloss caused by a treatment system is important, especially when a treatment system is retrofitted to a pre-existing drain pipe or ditchline.
Thus, the need exists for solutions to the above problems with the prior art.